Conventional fixed mast antennas mounted to and extending from vehicle bodies have generally been known to provide adequate gain for receiving radio signals. However, these antennas have drawbacks in that they are generally unsightly and also are vulnerable to bending and breakage. Concealed antennas, on the other hand, do not have the drawbacks associated with the conventional antennas in that typically they are flush mounted directly to a glass panel or an isolated section of sheet metal in the vehicle.
Nonetheless, concealed antennas do generally encounter a problem in that they are generally configured small in order to fit onto a particular window or body panel. This can be particularly true for some vehicles in that there may only be a very few small panels, such as windows or isolated body panels, available given the shape of the particular vehicle. Thus, these surfaces may be small relative to the wavelengths of the signals one wishes to receive. For example, signals in the AM frequency band. For these antennas, then, a concern arises with having good reception in the AM frequency band because of a lack of low frequency gain due to the small size of the antenna. To account for this, the systems generally require the use of an AM amplifier module to get sufficient gain to overcome cable and mismatch losses and still have an adequate signal.
While some have attempted to overcome this concern by mounting concealed antennas on multiple surfaces of the vehicle, they are generally more complex than desirable or require other amplification, filtering or switching components to provide enough gain for an adequate signal in the frequency ranges desired.
Thus, a simple, concealed antenna system is desired that will provide adequate gain for both high and low frequencies, with the flexibility to configure the system for various vehicle designs.